Sinner's Serve

Jannik Sinner makes some adjustments to avoid standing still

Aug 8, 2021

Jannik Sinner has put a stop to his mid-season slump in form to reach the Washington final this week. Tonight he plays Mackenzie McDonald for the trophy.

Something interesting happened with Sinner’s serve after his round one loss to Jack Draper on the grass at Queens a month or so ago. Sinner went back to the serving motion he used throughout his junior career up until mid 2018.

Here’s the split screen:

And if that was a bit fast, here’s the slow-mo:

There are a few changes across the three panels but the most important and obvious thing to notice is that:

In his juniors-2018 motion (left panel) he’s using the ‘platform’ stance where both feet stay in the same position until lift-off.
In the 2018-June 2021 motion (middle panel) he switched to the ‘pinpoint’ stance where he starts with feet further apart and then drags his back foot to meet his front foot pre-lift-off.
And in the June 2021- motion (right panel) he’s gone back to something close to his original motion.

One style isn’t ‘better’ than the other. Plenty of good servers have used either, for example Roger Federer and Pete Sampras uses/used the platform stance, and Nick Kyrgios and Ivo Karlovic use the pinpoint stance. There are also plenty of variations and hybrids of the two techniques.

The most basic advantage of the platform stance is that weight transfer from back foot to front foot should be smooth and help make the motion fluid and easily repeatable (as well as providing good horizontal drive). The disadvantage is that in theory there’s less biomechanical help with vertical drive and push-off. However, some of the best platform servers, e.g Sampras, managed to use a hell of a lot of hip and shoulder rotation in their platform stances to help generate the necessary extra power.

The most basic advantage of the pinpoint stance is in theory more explosive speed (vertical drive) and power with push-off potential from both feet closer together. The disadvantage is that you’re adding another moving part to the serve motion, a shot which tends to be at its best when the movement is as balanced and fluid, and the toss as accurate, as possible.

To be clear, at the pro level, the body control these players posses is so good that these guys will almost always be able to serve well in either stance. It usually just comes down to personal preference. After all, a player’s serve is only as good as their ability to hit repeatable, hard-to-return serves under pressure. A guy who can consistently hit 125mph 1st serves accurately into the corners, to hit his spots, is obviously a much better server than a player who can hit 130-135mph bombs less accurately and less repeatably, especially on the big points. Tweaks like these are just Sinner trying to find the balance which works best for him.

Sinner adapting

The great thing about Sinner playing around with this stuff is that he, and his excellent coach Riccardo Piatti, are tweaking things based on his development. This is exactly what you’d hope for a young player, especially considering that 1st serve potency has been an occasional area of weakness for Sinner in the last year or so:

In 2020 and 2021 before the service motion change, Sinner played 17 matches on hard courts where his 1st serve points won dropped below 70% (the average 1st serve points won performance for the tour is well above 70%):

The losses and first serve performances against Zverev and Medvedev are understandable, as both are good returners. But there are multiple opponents on that list who posting a 60%ish first serve win rate against is bad news. After all, none of Shapovalov, Bublik nor Hurkacz are known for their 1st serve return performance.

Sinner won fewer than half of those matches. And the Miami Masters final loss against Hurkacz was a particularly stark reminder of how few free points Sinner’s first serve can sometimes provide.

Since Sinner only made the change to his service motion very recently, the sample of matches since is extremely small. But what we have seen so far has been tentatively encouraging. The Italian’s 1st serve points won in Atlanta and Washington (his first hard court events since the service change) sits at 83%, and he’s yet to drop below that 70% first serve points won mark this week (against Korda, who is the eight best 1st serve returner on tour in the past 12 months, Sinner won 72%). Sinner’s ace rate also sits at 8.2% in the past 10 days compared to his 2020/21 hard court average of 5.4%. The avg service speeds are similar pre and post stance change however, so there’s no immediate indication that the Italian is suddenly getting significant extra pop off his serves. But again, it’s early days.

The above isn’t meant to be read as proof that what Sinner and Piatti are doing is necessarily working. It’s far too early to definitively tell (I’ll update this later this year with some more data on ace rates, unreturned rates and service points won). But it is meant to be read as an encouraging sign that Sinner and his team are well aware of what performance issues exist, and that they’re working on addressing them. At the end of the day that’s all you can really ask for rising stars like Jannik Sinner: a mindset of development and a hatred for staying static against the backdrop of the perpetually moving machine that is the competitive landscape of pro tennis.

Keep an eye out for that 1st serve against McDonald tonight, and in the months to come. Maybe the tweak will fail to produce results. Maybe it’ll bump up that 1st serve performance. But either way, Sinner isn’t standing still.

— MW

If you have any questions on the above, let me know in the comments. No question is dumb.

I’ll see you on Thursday.

Twitter @MattRacquet

The Racquet goes out twice a week, a (free) topical piece every Thursday and a (paid) analysis piece every Sunday/Monday.

Top: Casey Sykes/Getty

Left panel video credit. Middle panel video credit.

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